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314 lines
13 KiB
XML
314 lines
13 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd.time">
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<refentryinfo>
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<title>systemd.time</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.time</refentrytitle>
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<manvolnum>7</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.time</refname>
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<refpurpose>Time and date specifications</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<para>In systemd, timestamps, time spans, and calendar events are
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displayed and may be specified in closely related syntaxes.</para>
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</refsect1>
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<refsect1>
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<title>Displaying Time Spans</title>
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<para>Time spans refer to time durations. On display, systemd will
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present time spans as a space-separated series of time values each
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suffixed by a time unit.</para>
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<programlisting>2h 30min</programlisting>
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<para>All specified time values are meant to be added up. The
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above hence refers to 150 minutes.</para>
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</refsect1>
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<refsect1>
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<title>Parsing Time Spans</title>
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<para>When parsing, systemd will accept the same time span syntax.
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Separating spaces may be omitted. The following time units are
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understood:</para>
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<itemizedlist>
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<listitem><para>usec, us</para></listitem>
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<listitem><para>msec, ms</para></listitem>
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<listitem><para>seconds, second, sec, s</para></listitem>
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<listitem><para>minutes, minute, min, m</para></listitem>
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<listitem><para>hours, hour, hr, h</para></listitem>
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<listitem><para>days, day, d</para></listitem>
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<listitem><para>weeks, week, w</para></listitem>
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<listitem><para>months, month, M (defined as 30.44 days)</para></listitem>
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<listitem><para>years, year, y (define as 365.25 days)</para></listitem>
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</itemizedlist>
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<para>If no time unit is specified, generally seconds are assumed,
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but some exceptions exist and are marked as such. In a few cases
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<literal>ns</literal>, <literal>nsec</literal> is accepted too,
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where the granularity of the time span allows for this.</para>
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<para>Examples for valid time span specifications:</para>
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<programlisting>2 h
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2hours
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48hr
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1y 12month
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55s500ms
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300ms20s 5day</programlisting>
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</refsect1>
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<refsect1>
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<title>Displaying Timestamps</title>
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<para>Timestamps refer to specific, unique points in time. On
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display, systemd will format these in the local timezone as
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follows:</para>
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<programlisting>Fri 2012-11-23 23:02:15 CET</programlisting>
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<para>The weekday is printed according to the locale choice of the
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user.</para>
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</refsect1>
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<refsect1>
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<title>Parsing Timestamps</title>
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<para>When parsing, systemd will accept a similar syntax, but
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expects no timezone specification, unless it is given as the
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literal string "UTC". In this case, the time is considered in UTC,
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otherwise in the local timezone. The weekday specification is
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optional, but when the weekday is specified, it must either be in
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the abbreviated (<literal>Wed</literal>) or non-abbreviated
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(<literal>Wednesday</literal>) English language form (case does
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not matter), and is not subject to the locale choice of the user.
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Either the date, or the time part may be omitted, in which case
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the current date or 00:00:00, respectively, is assumed. The seconds
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component of the time may also be omitted, in which case ":00" is
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assumed. Year numbers may be specified in full or may be
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abbreviated (omitting the century).</para>
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<para>A timestamp is considered invalid if a weekday is specified
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and the date does not actually match the specified day of the
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week.</para>
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<para>When parsing, systemd will also accept a few special
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placeholders instead of timestamps: <literal>now</literal> may be
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used to refer to the current time (or of the invocation of the
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command that is currently executed). <literal>today</literal>,
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<literal>yesterday</literal>, and <literal>tomorrow</literal> refer to
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00:00:00 of the current day, the day before, or the next day,
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respectively.</para>
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<para>When parsing, systemd will also accept relative time
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specifications. A time span (see above) that is prefixed with
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<literal>+</literal> is evaluated to the current time plus the
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specified time span. Correspondingly, a time span that is prefixed
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with <literal>-</literal> is evaluated to the current time minus
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the specified time span. Instead of prefixing the time span with
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<literal>+</literal> or <literal>-</literal>, it may also be
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suffixed with a space and the word <literal>left</literal> or
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<literal>ago</literal>.</para>
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<para>Finally, a timespan prefixed with <literal>@</literal> is
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evaluated relative to the UNIX time epoch 1st Jan, 1970,
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00:00.</para>
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<para>Examples for valid timestamps and their normalized form
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(assuming the current time was 2012-11-23 18:15:22 and the timezone
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was UTC+8, for example TZ=Asia/Shanghai):</para>
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<programlisting>Fri 2012-11-23 11:12:13 → Fri 2012-11-23 11:12:13
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2012-11-23 11:12:13 → Fri 2012-11-23 11:12:13
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2012-11-23 11:12:13 UTC → Fri 2012-11-23 19:12:13
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2012-11-23 → Fri 2012-11-23 00:00:00
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12-11-23 → Fri 2012-11-23 00:00:00
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11:12:13 → Fri 2012-11-23 11:12:13
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11:12:13.9900009 → Fri 2012-11-23 11:12:13
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format_timestamp_us: Fri 2012-11-23 11:12:13.990000
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11:12 → Fri 2012-11-23 11:12:00
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now → Fri 2012-11-23 18:15:22
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today → Fri 2012-11-23 00:00:00
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today UTC → Fri 2012-11-23 16:00:00
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yesterday → Fri 2012-11-22 00:00:00
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tomorrow → Fri 2012-11-24 00:00:00
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+3h30min → Fri 2012-11-23 21:45:22
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+3h30min UTC → -EINVAL
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-5s → Fri 2012-11-23 18:15:17
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11min ago → Fri 2012-11-23 18:04:22
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11min ago UTC → -EINVAL
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@1395716396 → Tue 2014-03-25 03:59:56</programlisting>
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<para>Note that timestamps printed by systemd will not be parsed
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correctly by systemd, as the timezone specification is not
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accepted, and printing timestamps is subject to locale settings
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for the weekday, while parsing only accepts English weekday
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names.</para>
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<para>In some cases, systemd will display a relative timestamp
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(relative to the current time, or the time of invocation of the
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command) instead or in addition to an absolute timestamp as
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described above. A relative timestamp is formatted as
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follows:</para>
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<para>2 months 5 days ago</para>
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<para>Note that any relative timestamp will also parse correctly
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where a timestamp is expected. (see above)</para>
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</refsect1>
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<refsect1>
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<title>Calendar Events</title>
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<para>Calendar events may be used to refer to one or more points
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in time in a single expression. They form a superset of the
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absolute timestamps explained above:</para>
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<programlisting>Thu,Fri 2012-*-1,5 11:12:13</programlisting>
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<para>The above refers to 11:12:13 of the first or fifth day of
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any month of the year 2012, but only if that day is a Thursday or
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Friday.</para>
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<para>The weekday specification is optional. If specified, it
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should consist of one or more English language weekday names,
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either in the abbreviated (Wed) or non-abbreviated (Wednesday)
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form (case does not matter), separated by commas. Specifying two
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weekdays separated by <literal>-</literal> refers to a range of
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continuous weekdays. <literal>,</literal> and <literal>-</literal>
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may be combined freely.</para>
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<para>In the date and time specifications, any component may be
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specified as <literal>*</literal> in which case any value will
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match. Alternatively, each component can be specified as a list of
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values separated by commas. Values may also be suffixed with
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<literal>/</literal> and a repetition value, which indicates that
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the value and all values plus multiples of the repetition value
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are matched.</para>
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<para>The seconds component may contain decimal fractions both in
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the value and the repetition. All fractions are rounded to 6
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decimal places.</para>
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<para>Either time or date specification may be omitted, in which
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case the current day and 00:00:00 is implied, respectively. If the
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second component is not specified, <literal>:00</literal> is
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assumed.</para>
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<para>A timezone specification is not expected, unless it is given
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as the literal string "UTC", similarly to timestamps.</para>
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<para>The special expressions
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<literal>minutely</literal>,
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<literal>hourly</literal>, <literal>daily</literal>,
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<literal>monthly</literal>, <literal>weekly</literal>,
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<literal>yearly</literal>,
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<literal>quarterly</literal>,
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<literal>semiannually</literal> may be used as
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calendar events which refer to
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<literal>*-*-* *:*:00</literal>,
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<literal>*-*-* *:00:00</literal>,
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<literal>*-*-* 00:00:00</literal>,
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<literal>*-*-01 00:00:00</literal>,
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<literal>Mon *-*-* 00:00:00</literal>,
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<literal>*-01-01 00:00:00</literal>,
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<literal>*-01,04,07,10-01 00:00:00</literal> and
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<literal>*-01,07-01 00:00:00</literal>, respectively.
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</para>
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<para>Examples for valid timestamps and their
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normalized form:</para>
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<programlisting> Sat,Thu,Mon-Wed,Sat-Sun → Mon-Thu,Sat,Sun *-*-* 00:00:00
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Mon,Sun 12-*-* 2,1:23 → Mon,Sun 2012-*-* 01,02:23:00
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Wed *-1 → Wed *-*-01 00:00:00
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Wed-Wed,Wed *-1 → Wed *-*-01 00:00:00
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Wed, 17:48 → Wed *-*-* 17:48:00
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Wed-Sat,Tue 12-10-15 1:2:3 → Tue-Sat 2012-10-15 01:02:03
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*-*-7 0:0:0 → *-*-07 00:00:00
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10-15 → *-10-15 00:00:00
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monday *-12-* 17:00 → Mon *-12-* 17:00:00
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Mon,Fri *-*-3,1,2 *:30:45 → Mon,Fri *-*-01,02,03 *:30:45
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12,14,13,12:20,10,30 → *-*-* 12,13,14:10,20,30:00
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mon,fri *-1/2-1,3 *:30:45 → Mon,Fri *-01/2-01,03 *:30:45
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03-05 08:05:40 → *-03-05 08:05:40
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08:05:40 → *-*-* 08:05:40
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05:40 → *-*-* 05:40:00
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Sat,Sun 12-05 08:05:40 → Sat,Sun *-12-05 08:05:40
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Sat,Sun 08:05:40 → Sat,Sun *-*-* 08:05:40
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2003-03-05 05:40 → 2003-03-05 05:40:00
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05:40:23.4200004/3.1700005 → 05:40:23.420000/3.170001
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2003-03-05 05:40 UTC → 2003-03-05 05:40:00 UTC
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2003-03-05 → 2003-03-05 00:00:00
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03-05 → *-03-05 00:00:00
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hourly → *-*-* *:00:00
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daily → *-*-* 00:00:00
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daily UTC → *-*-* 00:00:00 UTC
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monthly → *-*-01 00:00:00
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weekly → Mon *-*-* 00:00:00
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yearly → *-01-01 00:00:00
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annually → *-01-01 00:00:00
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*:2/3 → *-*-* *:02/3:00</programlisting>
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<para>Calendar events are used by timer units, see
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<citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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